<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            /* perspective: 300px; */
        }

        .box {
            position: relative;
            width: 300px;
            height: 300px;
            /* background-color: #ccc; */
            margin: 100px auto;
            text-align: center;
            transition: all .7s;
            /* 让背面的紫色盒子保留立体空间 */
            transform-style: preserve-3d;
            backface-visibility: hidden;

        }

        .box:hover {
            transform: rotateY(180deg);
        }


        .box div {
            position: absolute;
            width: 300px;
            height: 300px;
            border-radius: 50%;
            top: 0;
            left: 0;
            line-height: 300px;
            font-size: 30px;
            color: #fff;
             /* backface-visibility: hidden; */

        }

        .f1 {
            background-color: #f00;
            /* transform: translateZ(1px); */

        }

        .f2 {
            background-color: purple;
            transform: rotateY(180deg);
        }
    </style>
</head>

<body>
    <div class="box">

        <div class="f2">欧克</div>
        <div class="f1">我的</div>
    </div>

</body>

</html>